By preference the Andamanese are exogamous as regards sept and endogamous as regards tribe.
It was not only by the formation of ever new endogamous castes and sub-castes that the system gained in extent and intricacy, but even more so by the constant subdivision of the castes into numerous exogamous groups or septs, themselves often involving gradations of social status important enough to seriously affect the possibility of intermarriage, already hampered by various other restrictions.
The population is divided into two exogamous classes.
These two birds in many tribes give names to the two great exogamous and intermarrying divisions; in their case there is a va et vient of divine, human and theriomorphic elements, just as in the Greek myths of Zeus.